<article class="" id="post-">
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<h1 class="entry-title">.index()</h1>
<div class="entry-meta">
						所属分类：<span class="category"><a href="/category/miscellaneous/">杂项</a> &gt; <a href="/category/miscellaneous/dom-element-methods/">DOM 元素方法</a></span>
<span class="pull-right">英文文档：<a href="https://api.jquery123.com/index/" target="_blank">.index()</a></span>
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<!-- .entry-header -->
<div class="entry-content">
<article class="entry method" id="index1"><h2 class="section-title">
<span class="name">.index()</span><span class="returns">返回: <a href="/Types/#Number">Number</a></span>
</h2>
<div class="entry-wrapper">
<p class="desc"><strong>描述: </strong>从匹配的元素中搜索给定元素的索引值，从0开始计数。</p>
<ul class="signatures">
<li class="signature" id="index">
<h4 class="name">
<span class="version-details">添加的版本: <a href="/category/version/1.4/">1.4</a></span>.index()</h4>
<ul><li><div class="null-signature">这个方法不接受任何参数。</div></li></ul>
</li>
<li class="signature" id="index-selector">
<h4 class="name">
<span class="version-details">添加的版本: <a href="/category/version/1.4/">1.4</a></span>.index( selector )</h4>
<ul><li>
<div><strong>selector</strong></div>
<div>类型: <a href="/Types/#Selector">Selector</a>
</div>
<div>一个选择器，代表一个jQuery对象，将会从这个对象中查找元素。</div>
</li></ul>
</li>
<li class="signature" id="index-element">
<h4 class="name">
<span class="version-details">添加的版本: <a href="/category/version/1.0/">1.0</a></span>.index( element )</h4>
<ul><li>
<div><strong>element</strong></div>
<div>类型: <a href="/Types/#Element,%20jQuery">Element, jQuery</a>
</div>
<div>将要用于查找的DOM元素，或者jQuery对象中的第一个元素。</div>
</li></ul>
</li>
</ul>
<div class="longdesc" id="entry-longdesc">
<h4>Return Values（返回值）</h4>
<p>如果不传递任何参数给 <code>.index()</code> 方法，则返回值就是jQuery对象中第一个元素相对于它同辈元素的位置。</p>
<p>如果在一组元素上调用 <code>.index()</code> ，并且参数是一个DOM元素或jQuery对象， <code>.index()</code> 返回值就是传入的元素相对于原先集合的位置。</p>
<p>如果参数是一个选择器， <code>.index()</code> 返回值就是原先元素相对于选择器匹配元素的位置。如果找不到匹配的元素，则 <code>.index()</code> 返回 -1.</p>
<h4>Detail（细节）</h4>
<p><code>.get()</code> 接受一个索引值参数并返回对应的DOM节点， <code>.index()</code> 与其正好相反，接受一个DOM节点然后返回其索引值。假设页面上有个简单的无序列表：</p>
<div class="syntaxhighlighter xml nogutter">
<table>
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<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
<div class="line n4">4</div>
<div class="line n5">5</div>
</td>
<td class="code">
<pre><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"foo"</span>&gt;</span>foo<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"bar"</span>&gt;</span>bar<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"baz"</span>&gt;</span>baz<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">ul</span>&gt;</span></code></div></div></pre>
</td>
</tr>
</tbody>
</table>
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<p>如果我们获取了三个li中的一个元素（例如通过DOM函数，或者事件处理函数中的上下文this）， <code>.index()</code> 能够在匹配的元素中找到这个列表项：</p>
<div class="syntaxhighlighter javascript nogutter">
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<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
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<td class="code">
<pre><div class="container"><div class="line"><code><span class="keyword">var</span> listItem = document.getElementById(<span class="string">'bar'</span>);</code></div></div><div class="container"><div class="line"><code>alert(<span class="string">'Index: '</span> + $(<span class="string">'li'</span>).index(listItem));</code></div></div><div class="container"><div class="line"><code>We get back the zero-based position of the list item:</code></div></div></pre>
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</tr>
</tbody>
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<p>
<span class="output">Index: 1</span>
</p>
<p>类似的，如果我们获得一个jQuery对象，该对象是三个列表项之一， <code>.index()</code> 也能用于搜索那个列表项：</p>
<div class="syntaxhighlighter javascript nogutter">
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<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
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<pre><div class="container"><div class="line"><code><span class="keyword">var</span> listItem = $(<span class="string">'#bar'</span>);</code></div></div><div class="container"><div class="line"><code>alert(<span class="string">'Index: '</span> + $(<span class="string">'li'</span>).index(listItem));</code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<p>我们就能得到这个li所在的位置，从0开始计数的：</p>
<p>
<span class="output">Index: 1</span>
</p>
<p>注意，如果作为 <code>.index()</code> 参数使用的jQuery集合含有多个元素，则只会使用第一个：</p>
<div class="syntaxhighlighter javascript nogutter">
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<tbody>
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<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
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<td class="code">
<pre><div class="container"><div class="line"><code><span class="keyword">var</span> listItems = $(<span class="string">'li:gt(0)'</span>);</code></div></div><div class="container"><div class="line"><code>alert(<span class="string">'Index: '</span> + $(<span class="string">'li'</span>).index(listItems));</code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<p>我们得到了匹配的li集合中，第一个元素的位置，从0开始计数。</p>
<p>
<span class="output">Index: 1</span>
</p>
<p>如果我们将一个字符串传递给 <code>.index()</code> 方法，这个字符串会被解析成jQuery选择器，将会定位到调用 <code>.index()</code> 的jQuery对象中第一个元素，相对于由这个选择器匹配到的元素集合中的位置：</p>
<div class="syntaxhighlighter javascript nogutter">
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<tbody>
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<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
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<pre><div class="container"><div class="line"><code><span class="keyword">var</span> listItem = $(<span class="string">'#bar'</span>);</code></div></div><div class="container"><div class="line"><code>alert(<span class="string">'Index: '</span> + listItem.index(<span class="string">'li'</span>));</code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<p>我们就能得到这个列表项所在的位置，从0开始计数的：</p>
<p>
<span class="output">Index: 1</span>
</p>
<p>如果我们忽略参数， <code>.index()</code> 将返回集合中第一个元素相对于其同辈元素的位置：</p>
<div class="syntaxhighlighter javascript nogutter">
<table>
<tbody>
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<td class="gutter">
<div class="line n1">1</div>
</td>
<td class="code">
<pre><div class="container"><div class="line"><code>alert(<span class="string">'Index: '</span> + $(<span class="string">'#bar'</span>).index());</code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<p>又一次，我们得到了这个li从0开始数的位置。</p>
<p>
<span class="output">Index: 1</span>
</p>
</div>
<section class="entry-examples" id="entry-examples"><header><h2 class="underline">例子:</h2></header><div class="entry-example" id="example-0">
<h4>Example: <span class="desc">点击后，返回那个div在页面上的索引值(从0开始计数)。</span>
</h4>
<div class="syntaxhighlighter xml ">
<table>
<tbody>
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<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
<div class="line n4">4</div>
<div class="line n5">5</div>
<div class="line n6">6</div>
<div class="line n7">7</div>
<div class="line n8">8</div>
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<div class="line n11">11</div>
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<div class="line n14">14</div>
<div class="line n15">15</div>
<div class="line n16">16</div>
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<div class="line n18">18</div>
<div class="line n19">19</div>
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<div class="line n21">21</div>
<div class="line n22">22</div>
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<div class="line n24">24</div>
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<td class="code">
<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!DOCTYPE html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"></span></code></div></div><div class="container"><div class="line"><code><span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">background</span>:<span class="value">yellow;</span></span> <span class="rule"><span class="attribute">margin</span>:<span class="value"><span class="number">5</span>px;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code><span class="tag">span</span> <span class="rules">{ <span class="rule"><span class="attribute">color</span>:<span class="value">red;</span></span> <span class="rule">}</span></span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">span</span>&gt;</span>Click a div!<span class="tag">&lt;/<span class="title">span</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span>&gt;</span>First div<span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span>&gt;</span>Second div<span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span>&gt;</span>Third div<span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">script</span>&gt;</span><span class="javascript"></span></code></div></div><div class="container"><div class="line"><code>$(<span class="string">"div"</span>).click(<span class="function"><span class="keyword">function</span> <span class="params">()</span> {</span></code></div></div><div class="container"><div class="line"><code>  <span class="comment">// this is the dom element clicked</span></code></div></div><div class="container"><div class="line"><code>  <span class="keyword">var</span> index = $(<span class="string">"div"</span>).index(<span class="keyword">this</span>);</code></div></div><div class="container"><div class="line"><code>  $(<span class="string">"span"</span>).text(<span class="string">"That was div index #"</span> + index);</code></div></div><div class="container"><div class="line"><code>});</code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div>
<div class="entry-example" id="example-1">
<h4>Example: <span class="desc">返回ID为bar的元素的索引值。</span>
</h4>
<div class="syntaxhighlighter xml ">
<table>
<tbody>
<tr>
<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
<div class="line n4">4</div>
<div class="line n5">5</div>
<div class="line n6">6</div>
<div class="line n7">7</div>
<div class="line n8">8</div>
<div class="line n9">9</div>
<div class="line n10">10</div>
<div class="line n11">11</div>
<div class="line n12">12</div>
<div class="line n13">13</div>
<div class="line n14">14</div>
<div class="line n15">15</div>
<div class="line n16">16</div>
<div class="line n17">17</div>
<div class="line n18">18</div>
</td>
<td class="code">
<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!DOCTYPE html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"><span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">font-weight</span>:<span class="value"> bold;</span></span> <span class="rule"><span class="attribute">color</span>:<span class="value"> <span class="hexcolor">#090</span>;</span></span> <span class="rule">}</span></span></span><span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"foo"</span>&gt;</span>foo<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"bar"</span>&gt;</span>bar<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"baz"</span>&gt;</span>baz<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">script</span>&gt;</span><span class="javascript"><span class="keyword">var</span> listItem = $(<span class="string">'#bar'</span>);</span></code></div></div><div class="container"><div class="line"><code>    $(<span class="string">'div'</span>).html( <span class="string">'Index: '</span> + $(<span class="string">'li'</span>).index(listItem) );<span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div>
<div class="entry-example" id="example-2">
<h4>Example: <span class="desc">返回jQuery集合中第一项的索引值。</span>
</h4>
<div class="syntaxhighlighter xml ">
<table>
<tbody>
<tr>
<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
<div class="line n4">4</div>
<div class="line n5">5</div>
<div class="line n6">6</div>
<div class="line n7">7</div>
<div class="line n8">8</div>
<div class="line n9">9</div>
<div class="line n10">10</div>
<div class="line n11">11</div>
<div class="line n12">12</div>
<div class="line n13">13</div>
<div class="line n14">14</div>
<div class="line n15">15</div>
<div class="line n16">16</div>
<div class="line n17">17</div>
<div class="line n18">18</div>
<div class="line n19">19</div>
</td>
<td class="code">
<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!DOCTYPE html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"><span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">font-weight</span>:<span class="value"> bold;</span></span> <span class="rule"><span class="attribute">color</span>:<span class="value"> <span class="hexcolor">#090</span>;</span></span> <span class="rule">}</span></span></span><span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"foo"</span>&gt;</span>foo<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"bar"</span>&gt;</span>bar<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"baz"</span>&gt;</span>baz<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">script</span>&gt;</span><span class="javascript"><span class="keyword">var</span> listItems = $(<span class="string">'li:gt(0)'</span>);</span></code></div></div><div class="container"><div class="line"><code>$(<span class="string">'div'</span>).html( <span class="string">'Index: '</span> + $(<span class="string">'li'</span>).index(listItems) );</code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div>
<div class="entry-example" id="example-3">
<h4>Example: <span class="desc">返回ID为bar的元素相对于所有 &lt;li&gt; 元素的索引值。</span>
</h4>
<div class="syntaxhighlighter xml ">
<table>
<tbody>
<tr>
<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
<div class="line n4">4</div>
<div class="line n5">5</div>
<div class="line n6">6</div>
<div class="line n7">7</div>
<div class="line n8">8</div>
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</td>
<td class="code">
<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!DOCTYPE html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"><span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">font-weight</span>:<span class="value"> bold;</span></span> <span class="rule"><span class="attribute">color</span>:<span class="value"> <span class="hexcolor">#090</span>;</span></span> <span class="rule">}</span></span></span><span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"foo"</span>&gt;</span>foo<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"bar"</span>&gt;</span>bar<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"baz"</span>&gt;</span>baz<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">script</span>&gt;</span><span class="javascript">$(<span class="string">'div'</span>).html(<span class="string">'Index: '</span> +  $(<span class="string">'#bar'</span>).index(<span class="string">'li'</span>) );</span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div>
<div class="entry-example" id="example-4">
<h4>Example: <span class="desc">返回ID为bar的元素相对于同辈的索引值。</span>
</h4>
<div class="syntaxhighlighter xml ">
<table>
<tbody>
<tr>
<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
<div class="line n4">4</div>
<div class="line n5">5</div>
<div class="line n6">6</div>
<div class="line n7">7</div>
<div class="line n8">8</div>
<div class="line n9">9</div>
<div class="line n10">10</div>
<div class="line n11">11</div>
<div class="line n12">12</div>
<div class="line n13">13</div>
<div class="line n14">14</div>
<div class="line n15">15</div>
<div class="line n16">16</div>
<div class="line n17">17</div>
<div class="line n18">18</div>
</td>
<td class="code">
<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!DOCTYPE html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"><span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">font-weight</span>:<span class="value"> bold;</span></span> <span class="rule"><span class="attribute">color</span>:<span class="value"> <span class="hexcolor">#090</span>;</span></span> <span class="rule">}</span></span></span><span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"foo"</span>&gt;</span>foo<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"bar"</span>&gt;</span>bar<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"baz"</span>&gt;</span>baz<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">script</span>&gt;</span><span class="javascript"><span class="keyword">var</span> barIndex = $(<span class="string">'#bar'</span>).index();</span></code></div></div><div class="container"><div class="line"><code>$(<span class="string">'div'</span>).html( <span class="string">'Index: '</span> +  barIndex );<span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div>
<div class="entry-example" id="example-5">
<h4>Example: <span class="desc">由于没有元素的ID为foobar，所以返回 -1。</span>
</h4>
<div class="syntaxhighlighter xml ">
<table>
<tbody>
<tr>
<td class="gutter">
<div class="line n1">1</div>
<div class="line n2">2</div>
<div class="line n3">3</div>
<div class="line n4">4</div>
<div class="line n5">5</div>
<div class="line n6">6</div>
<div class="line n7">7</div>
<div class="line n8">8</div>
<div class="line n9">9</div>
<div class="line n10">10</div>
<div class="line n11">11</div>
<div class="line n12">12</div>
<div class="line n13">13</div>
<div class="line n14">14</div>
<div class="line n15">15</div>
<div class="line n16">16</div>
<div class="line n17">17</div>
<div class="line n18">18</div>
</td>
<td class="code">
<pre><div class="container"><div class="line"><code><span class="doctype">&lt;!DOCTYPE html&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">html</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">style</span>&gt;</span><span class="css"><span class="tag">div</span> <span class="rules">{ <span class="rule"><span class="attribute">font-weight</span>:<span class="value"> bold;</span></span> <span class="rule"><span class="attribute">color</span>:<span class="value"> <span class="hexcolor">#090</span>;</span></span> <span class="rule">}</span></span></span><span class="tag">&lt;/<span class="title">style</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">script</span> <span class="attribute">src</span>=<span class="value">"https://code.jquery.com/jquery-latest.js"</span>&gt;</span><span class="javascript"></span><span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">head</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"foo"</span>&gt;</span>foo<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"bar"</span>&gt;</span>bar<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code>  <span class="tag">&lt;<span class="title">li</span> <span class="attribute">id</span>=<span class="value">"baz"</span>&gt;</span>baz<span class="tag">&lt;/<span class="title">li</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">ul</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">div</span>&gt;</span><span class="tag">&lt;/<span class="title">div</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;<span class="title">script</span>&gt;</span><span class="javascript"><span class="keyword">var</span> foobar = $(<span class="string">"li"</span>).index( $(<span class="string">'#foobar'</span>) );</span></code></div></div><div class="container"><div class="line"><code>$(<span class="string">'div'</span>).html(<span class="string">'Index: '</span> + foobar);<span class="tag">&lt;/<span class="title">script</span>&gt;</span></code></div></div><div class="container"><div class="line"><code> </code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">body</span>&gt;</span></code></div></div><div class="container"><div class="line"><code><span class="tag">&lt;/<span class="title">html</span>&gt;</span></code></div></div></pre>
</td>
</tr>
</tbody>
</table>
</div>
<h4>Demo:</h4>
<div class="demo code-demo"></div>
</div></section>
</div></article> </div>
</article>